Diagnostic instruments for the psychiatric evaluation of infants and toddlers were developed, tested, and used. The subjects are 2 to 5 year-old-children of depressed and normal mothers seen in a project designed to study the environmental factors underlying the transmission of affective from parent to child. The instruments used in the initial evaluation of these children were a semi-structured play interview consisting of 3 10-minute segments: free play, doll play, and aggressive play. These interviews plus Achenbach Inventory plus a social history of the child were used to make a DSM III diagnosis or to describe various areas of concern. At present a new rating scale is being devised and tested for use with current subjects plus younger children, down to 1-1/2 years of age.